45 



may easily conceive how that exhalation loading 

 the air of the closed room became condensed on 

 the surface of the body, which its evolution 

 had tended to cool, as well as on the Florence 

 flask. 



And here we have another reason why im- 

 mersion in heated water or vapour is not so 

 easily endured as heated air, for during immer- 

 sion in heated water, especially, the conversion 

 of perspiration from the skin into invisible 

 vapour cannot take place, and the work must 

 fall upon the lungs alone. But there is another 

 cause whereby the body is enabled to resist the 

 effects of heat, and here we must look to the 

 condition of the blood itself. During subjection 

 to a high temperature, the pulse, or arterial 

 action, is augmented both in power and fre- 

 quency, and consequently more evaporable 

 fluid is sent to the excretory tubes of the skin 

 and lungs. But this is not all. Under the 

 influence of heat the blood becomes less 

 venalized, or deteriorated, and, in proportion as 

 it preserves its fluid arterial character, the 

 union of carbon and oxygen (that is, a gradual 

 combustion) is greatly diminished, whether in 

 the lungs or in the fine capillary vessels of the 

 body itself. With this diminution of internal 

 fire (for such it really is) is conjoined a dimi- 

 nution of temperature. We may state, then, as 

 an axiom, that at an elevated temperature there 

 will always be a diminished production of heat 

 within the body, seeing that the blood contains 

 a diminished quantity of combustible material, 



